This invention relates to high speed pumps, and more particularly to high speed pumps for Whirlpool and Spa applications.
Other similar devices primarily fall into five categories:
a. Close coupled end suction (non-self draining), low speed pump on single speed, A.C. induction motor. PA1 b. Close coupled end suction, self-draining, low speed pump on single speed, A.C. induction motor. PA1 C. Close coupled end suction (non-self draining), low speed pump on two speed, A.C. induction motor. PA1 d. Close coupled end suction, self-draining, low speed pump on variable speed, variable frequency induction motor. PA1 e. Belt driven, low speed submersible pump powered by high speed series wound universal motor (portable Whirlpool units only).
All of the above categories of Whirlpool pumps, provide flow and pressure to the liquid to be circulated in the normal manner consistent with single stage centrifugal, Kinetic pumps, of radial vane, closed impeller construction. Substantially all of the Whirlpool pumps are driven by various types of induction motors, as is the case with most electric motor driven centrifugal pumps.
The biggest shortcoming with the above mentioned current devices is the inherent relative high cost of the motor. The size and, therefore, cost of the motor is inversely related to the motor speed. The higher the speed the smaller the size and the lower the cost. The maximum motor speed on normal household A.C. current is 3600 RPM, based on an A.C. induction motor, with the minimum number (two) of motor poles and 60 cycles per second current frequency in the USA. Devices have been developed for induction type A.C. motors which can vary the cycle frequency (and therefore motor speed) up or down, however, this does not reduce, but rather increases the complexity and cost of the motor plus controls package.
Even when the motor speed (and therefore pump speed) is increased by means of a variable frequency device, there is a limit to the speed of a conventional centrifugal pump in Whirlpool or Spa applications due to cavitation in the inlet of the impeller vanes. This is why belt-driven submersible pumps powered by high speed universal motors are stepped down to about 3600 RPM today. Further, conventional universal motors are inherently noisy and must normally operate at very high speeds (over 10,000 RPM) to provide sufficient cooling for the power levels required with a fixed installation Whirlpool pump.
Additionally, the following patents were developed in searching the various features of the invention:
______________________________________ Patent No. Inventor ______________________________________ 4,661,041 Hessler 3,384,022 Oshima 4,019,829 Knopfel et al. 4,449,889 Balje 4,523,900 Frey 4,642,023 Dunn 4,213,742 Henshaw 4,389,159 Sarvanne 4,518,311 Dernedde et al. 3,516,757 Baumann 4,126,360 Miller et al. 4,286,919 Yamaguchi 2,991,927 Quick 4,842,481 Collins 3,286,639 Hutton ______________________________________
Accordingly, the high speed pump for Whirlpool and Spa application of the invention overcomes the limitations of the prior art devices.